1. Field of the Invention
The present invention relates to the control of power modes for computer systems, and more particularly to control for switching between operating modes to protect various devices such as a hard disk drive.
2. Background
One of power saving schemes for a personal computer is switching it between operating states (hereinafter referred to as system operating modes). That is, when the personal computer is not used for a certain amount of time, the unnecessary operation of peripheral devices or internal components that are not employed is suspended to shut off their power needs and thus reduce the power consumption of the system. Such system operating modes typically include modes referred to as standby (suspend) mode and hibernation mode.
FIG. 7 is a schematic diagram of the hardware configuration of a typical personal computer. In FIG. 7, a CPU 701 performs various arithmetical and other operations under the control of a program such as an operating system (not shown). A main memory 702 is an internal storage from or into which data is directly read or written by the CPU 701, and which stores programs for controlling the CPU 701 or data for arithmetical operation. Generally, the main memory 702 is a volatile memory such as DRAM. An HDD 703 is a hard disk unit (Hard Disk Drive) employed as an external storage unit. A monitor 704 is an output unit for displaying the processed results by the CPU 701, and connected to the CPU 701 via a graphics display mechanism having a video memory (not shown). The monitor 704 may be a CRT display or an LCD (Liquid Crystal Display), for example. The personal computer system may include, or be connected to, various other peripheral devices according to the needs and desires of a user (not shown).
Among the system operating modes for power saving, in the standby mode, the power of the HDD 703 and monitor 704 is shut off, and other peripheral devices are placed in a least power consumption operation. However, in order to maintain the data residing in the main memory 702, it is necessary to continue to supply power to the main memory 702.
In contrast, in the hibernation mode, all the information including the contents of the main memory 702 and the contexts of various peripheral devices are written into the HDD 703 and all unnecessary power is shut off. Accordingly, no power is supplied to the main memory 702 while the system is in the hibernation mode. But, even when the power of the system is fully shut off, the system can be restored to its previous state by reading the saved data from the HDD 703 when the system power is next turned on.
In transitioning from any system operating mode to the hibernation mode, it is necessary to write a large amount of data into the HDD 703 in a certain time (20 seconds or more). On the other hand, it takes a much shorter time (usually 5 seconds or less) to transition to the standby mode, which is much simpler due to the lessened need for data transfer. Therefore, it is typical that when the system is not used for a short amount of time, the system transitions to the standby mode, and only when a certain amount of time has passed in the standby mode will the system automatically transition to the hibernation mode. For example, in the Windows® XP operating system from Microsoft Corporation, USA, power management is enabled on the basis of the ACPI (Advanced Configuration and Power Interface). For example, if a “max battery” power scheme is selected in the power options in the control panel, the control is provided such that the system enters the “standby mode” if the system is not employed for two minutes and the system only transitions to the hibernation mode after one hour of non-use. Other settings may be available in this and other operating systems which specify differing timeframes for the transition to each of these and other operating modes which may be available. Systems and operating systems may also be available which offer different or additional operating modes providing for other, varying degrees of power savings.
In controlling a system to transition to the hibernation mode after the elapse of a certain time in the standby mode, the system automatically starts the operation to write data into the HDD when the specified time has passed.
However, in a portable computer such as a notebook personal computer or PDA (Personal Digital Assistant), it sometimes occurs that the computer apparatus is in violent movement such as vibration, acceleration or rotation. If the operation of transitioning to the hybernation mode is started at this time, there is the possibility that the HDD may be damaged, along with other peripherals or components subject to damage if operated while moving. In this case, the worst-case scenario is that the HDD is disabled and the data in the HDD lost.
In particular, it is noted that a user typically takes care not to apply a severe vibration or shock to a computer apparatus under normal use, but a user may treat a computer in the standby mode as if it were in a power OFF state. Therefore, while in standby mode, there is a heightened possibility that the user may be relatively careless in handling the computer apparatus, increasing the chance of damage to the HDD upon transitioning to the hibernation mode.
To avoid some of the above problems and disadvantages, the system may be prepared for hibernation mode when transitioning to the standby mode (see U.S. Pat. No. 5,551,043, for example). That is, in the standby mode, the memory contents are written into the HDD, making the system ready for transitioning to the hibernation mode at any time. And if the conditions such as the elapse of a fixed time and a voltage drop of the battery are met, the power is shut off and the system enters the hibernation mode.
However, using this method, transitioning to the standby mode takes just as much time as entering the hibernation mode, resulting in lower availability of the system.
The same disadvantages may occur when the HDD is automatically accessed, such as when the system not only transitions to the hibernation mode, but also returns from the standby mode or hibernation mode under timer control.
Thus, in the light of the above-mentioned problems, it is an object of the present invention to protect components of a computer apparatus against a physical shock by controlling switching between system operating modes on the basis of the presence or absence of the physical motion of the computer apparatus such as vibration, acceleration and rotation.